Good day Peter!
A board between the sink and the icebox on which to sit was high on my list of jobs for next season. Maybe if the eBay gods are kind they will offer me a bronze folding pilot's seat -- just the thing for this job.
I was not enthousiastic about facing aft doing my navigating though.
However, you may be on to something. I once built a Murphy bed -- a bed that folds against the wall when not in use. On the back of the bed I mounted a desk.
So, take the ideas we have tossed around here in this thread. Rig a removable seat near the galley setup facing forward. The seat would preferably be attached to one quarterberth with a gap that would allow a person to pass without taking down the seat. One of those folding pilot seats would be just the thing.
Then make a box, 4-5" deep hinged to outside of the door of the head. Folded down when not in use it would not project much into the companionway. However, when the door of the head is open (i.e. door facing aft), the box could be folded up to the level of the galley. Voila -- a fair sized chart table, or additional galley counter space. If deadbolts were used to connect the box to the galley, this configuration would be very strong.
The only challenge would be that everything would heel when under sail. One would need to fasten everything down. (I suppose this is normal on our boats! )
Any other ideas?